JPS6131233Y2 - - Google Patents

Description

[Detailed description of the invention] The invention comprises a piston valve held in its starting position under spring force, which piston valve has a blind bore starting from the supply side, through which the piston An outflow hole protrudes radially from the cylindrical circumferential surface of the valve, and this outflow port terminates in the circumferential direction with a cylindrical widening part, or the hole edge is bent. , and is arranged in an annular groove in the cylindrical guide surface for the piston valve behind the radial outflow opening in the flow direction and surrounds the piston valve in a sealing manner. The present invention relates to an overpressure valve for underground hydraulic props in the mining industry operating in the pressure range from 200 to 600 bar for pressure liquid oil-water emulsions in the form of an exchangeable overpressure cartridge with a ring.

In underground coal mining operations, hydraulic struts that support the ground must provide support against the generation of unacceptably large internal pressures that occur under the action of ground loads. For this purpose, the working chamber of the column is connected to an overpressure valve, which opens a small unloading opening when a predetermined pressure is reached, and which opens again after the pressure in the column has been reduced. Close.

Various requirements are imposed on the acceptability of such overpressure valves. The sensitivity to pressure fluctuations must be extremely high to ensure that the overpressure valve responds reliably at a given pressure. On the other hand, in order for the overpressure valve to work without any problems, it must be insensitive to the harsh working conditions that are inevitable in underground mining operations. The overpressure patrol must be particularly suitable for oil-water emulsions and working pressures in the range of 500 bar.

The object of the invention is to create an overpressure valve for a hydraulic mine shaft with a high degree of functional reliability and at the same time a long service life. In practice, significant requirements are placed on the functional reliability of such overpressure valves. Such an overpressure valve must react immediately (without delay) when the column reaches its nominal pressure, so that pressure peaks are reduced. However, in this case the pressure in the column pressure chamber must not fall below permissible limits and must remain as far as possible within the nominal pressure range. The present invention takes into account these circumstances in underground shafts, and the object thereof is to create an overpressure valve suitable for this purpose and satisfying the above-mentioned conditions.

This problem is solved by the present invention as follows. That is, the cylindrical outer surface of the piston slider has a thread height of about 1 μm or less, and the O-ring is hydrolyzed, wear-resistant, and finished with a Shore hardness of about 90 Shore A and about 20 Shore A. % of elastomeric rubber, the ring thickness of the O-ring is at least approximately twice the diameter of the radial outflow opening of the piston valve, and the diameter of the O-ring is at least approximately twice the diameter of the radial outflow opening of the piston valve. The length of the annular gap from the end of the annular groove to the abutment surface is not significantly larger than the ring thickness of the O-ring, and the inner diameter of the abutment surface is slightly shorter than the annular groove. the piston valve is designed to be larger than the central diameter and configured such that the closing force provided by the spring acts on the abutment surface for the head of the piston valve outside the central diameter of the annular groove; This is solved by making the outer shape of the abutting surface of the head larger than the diameter of the annular groove.

The surface treatment of the outer surface of the piston valve, which has heretofore been neglected, yields a precise working style through the selection of the thread height as described above. The choice of material for the O-ring allows for invariance with the working fluid, the majority of which is water containing recalcitrant acids and other contaminants. The rubber elasticity and shore hardness allow a suitable deformation of the O-ring, while the deformability avoids destruction of the O-ring, especially in the area where the radial holes are formed. . In this regard, the inner diameter of the O-ring - taking into account the maximum tolerance dimensions in each case, of course - is the same as the diameter of the piston valve or -
Of course, it is important that the tolerance dimensions are the smallest - slightly shorter, so that only a small amount of sticking friction occurs between the piston valve and the O-ring. It has been found that the combination of the above features gives very advantageous results.

Furthermore, in the present invention, the transition portion from the cylindrical hole surface of the radial outflow hole to the cylindrical outer surface of the piston valve is smooth and polished while having a thread height of approximately 1 μm. being processed. This feature ensures that even if the surface of the O-ring is slightly damaged or worn due to contact action in the area where the radial outflow hole is formed, it can no longer fulfill its function. This helps prevent possible O-ring damage from occurring.

Furthermore, according to the present invention, the gap width of the annular gap between the piston valve and the cylindrical guide surface in the area behind the O-ring when viewed in the flow direction is approximately
It is 0.03~0.04mm. This configuration is O
- The annular gap present at the rear of the ring is important as it provides a certain throttling effect which results in a certain pressure balance and a slight deformation of the O-ring. However, on the other hand, it must be ensured that this annular gap allows a sufficiently large amount of liquid to flow through it per unit time without exceeding the limits of the flow rate. The O-ring is
It must have high strength (surface tension) to prevent it from sinking into the annular hole.

The design of the invention assumes that the length of the annular gap is in a constant ratio to the ring thickness of the O-ring when the valve is closed. This must be maintained at a minimum in order to reliably maintain the dynamic pressure and to keep the stroke of the piston valve and thus the reaction time of the valve relatively short.

Furthermore, the configuration of the invention prevents the forces acting on the piston valve from causing plastic deformations within the annular gap and the O-ring groove. The bulge of material remaining above the O-ring groove has only a small thickness and bends when the pressure transmitted from the head of the piston valve is high. However, such curvature dramatically increases the throttling resistance and reduces the deformability of the O-ring within its groove, resulting in a significant impairment of function.

The invention provides a piston-O-ring cartridge that is well suited to the conditions of practical use and enables techniques that were previously not thought possible with the same efficiency. As is known, the safety of the mine space in underground coal mine operations is guaranteed and the safety of the workers engaged in the operation is increased depending on the reliable functioning of the overpressure cartridge.

The invention will be described in detail below with reference to embodiments illustrated in the accompanying drawings.

The overpressure valve, generally designated 1, has a casing 2, which is perforated from the side along a central axis. An internal thread is cut into this bore 3 in its open area, through which the guide part 4 is screwed into this bore 3. The outer surface of this guide part is provided with a corresponding thread. In front of the end face of the guide part 4 that closes the hole 3, a spring disk 5 is movable longitudinally in the hole 3, and this spring disk is connected to a pressure spring 6.
is pressed in the direction of the guide part 4 via.
The guide part 4 has a central longitudinally oriented bore which forms a guide surface 7 for a piston valve 8 which can be slid therein. This piston valve 8 has a semicircular head 9 at its end projecting into the bore 3, which engages in a correspondingly formed semicircular recess in the spring plate 5. The piston valve 8 is provided with a central longitudinally oriented blind hole 11 from the end corresponding to the head 9, from which two radially opposed holes 11 are provided near the head 9. Outflow holes 12 are exposed. An outflow hole 12 widens conically in the direction of the cylindrical outer surface 13 of the piston valve 8 . An annular groove 14 is formed in the guide surface 7 between this outlet hole 12 and the head 9, and this annular groove accommodates an O-ring 15. Annular groove 1
Length a of the annular gap from the end of 4 to the contact surface 16
is the same as or smaller than the ring thickness b of the O-ring 15. The cylindrical guide surface 7 diverges and ends in the abutment surface 16 . The flow is thereby advantageously influenced by the overpressure valve 1. The abutment surface 16 is configured such that the resulting spring force 17 acts on the abutment surface 16 outside the central diameter c of the annular groove 14 . In the illustrated embodiment, the outer diameter d of the abutting surface 16 corresponds to the diameter of the head 9.
is larger than the outer diameter e of the annular groove 14. The cylindrical outer surface 13 of the piston valve 8 is precision polished and has a thread height of less than 1 μm. The transition from the cylindrical bore surface of the outlet hole 12 to the cylindrical outer surface 13 likewise has a thread height of less than 1 μm and is smooth and polished.

As a result of tests, the most suitable material for the O-ring 15 is water-hydrolyzable, highly abrasion-resistant, and finished rubber having a shore hardness of about 90 shore A and a rubber elastic modulus of about 20%. I understood.

The rubber elastic modulus mentioned above is the elastic deformation rate of rubber materials specified in the German Industrial Standard (DIN), that is, the pressure-deformation residual rate after constant deformation (R _D
V ) means. This pressure-deformation residual rate is a ratio obtained from the difference between the height of the sample before and after compression and the original height, and is determined by the following formula: R _DV = ho - hl/ho x 100% (in the formula, R _DV is The deformation value that still exists even after the rubber body is deformed under pressure and subsequently unloaded is expressed as ho
is the height of the rubber body before pressure deformation, and hl is the deformation value after pressure compression and subsequent natural recovery. ) With the configuration according to the invention, an increase in the life of the overpressure valve by more than 600% is achieved. In this case, the surface 13 of the piston slider 8 is (roughened to about 1 μm)
O is polished and therefore exists within the annular groove and is subject to strong deformation forces under significant hydraulic pressure.
- the ring is not damaged;

Furthermore, the O-ring is sized at least twice the diameter of the radial outflow hole 12 of the piston slider 8. Also, the inner diameter of the O-ring 15 is carefully adapted to the diameter of the piston slider 8. Moreover, the difference between the inner diameter of this O-ring and the diameter of the piston slider is only small.

The functions of the excess valve 1 are as follows.

The overpressure valve 1 is a cylindrical extension 18 that extends into a not-shown casing that communicates with the working chamber of the hydraulic column and into which it is screwed via an external thread of the guide part 4. It is. The working pressure propagates in the flow direction (arrow 19) into the overpressure valve. If the working pressure exceeds a predetermined working pressure, the piston valve 8 slides in the flow direction 19 against the force of the pressure spring 6. In this case, the outflow hole 12 is O-
It reaches within the end region of the cylindrical guide surface 7 which is located in the ring 15 or at the rear in the direction of flow 19 . In this case, a certain amount of emulsion is dissipated and this emulsion flows out through the outflow hole 21. If the pressure falls again below the predetermined pressure value, the push spring 6 presses the piston valve 8 again into the illustrated closed position, in which the passage through the overpressure valve is closed. The predetermined pressure value to which the overpressure valve responds is adjustable. This is done by varying the force of the pressure spring 6, which can be varied to a greater or lesser extent by further screwing the casing 2 into the guide part 4. Guide part 4 of casing 2
Fixation to the drain hole 21 is ensured by a fixing pin 22 inserted into the outflow hole 21.

The above-mentioned overpressure valve can be easily replaced as an overpressure cartridge, and is easy to handle in practice.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of an overpressure valve constructed according to the present invention, and FIG. 2 is a detailed enlarged view of FIG. 1. The symbols in the figure are 8...piston valve, 12...outflow hole, 13...outer surface, 14...annular groove, 15...O
-Ring, 16...Abutting surface, 17...Closing force.

Claims (1)

[Claims for Utility Model Registration] 1. A piston valve, which is held in its starting position under the force of a spring, and which has a blind hole starting from the supply side, through which the piston valve can be opened. An outflow hole protrudes radially from the cylindrical circumferential surface, and the outflow port terminates in the circumferential direction with a cylindrical widening part, or the hole edge is bent, and an O-ring which is arranged in an annular groove in the cylindrical guide surface for the piston valve behind the radial outlet opening in the flow direction and surrounds the piston valve in a sealing manner; Pressurized liquid oil in the form of a replaceable overpressure cartridge with
In an overpressure valve for underground hydraulic props for mining applications operating in the pressure range from 200 to 600 bar for water-type emulsions, the cylindrical outer surface 1 of the piston valve 8
3 has a thread height of approximately 1 μm or less, and O-
The ring 15 is made of a hydrolysis-resistant, abrasion-resistant and finished rubber with a shore hardness of about 90 shore A and a elastomer elasticity of about 20%;
- the ring thickness b of the ring 15 is at least approximately twice as large as the diameter f of the radial outflow opening 12 of the piston valve 8, and the diameter of the O-ring 15 is only slightly larger than the diameter of the piston valve 8; The length a from the end of the annular groove 14 of the annular gap to the contact surface 16 is slightly shorter than that of the O-ring 1.
5, the inner diameter of the contact surface 16 is formed larger than the center diameter of the annular groove 14, and the closing force 17 obtained by the spring 6 is applied to the center of the annular groove 14. The outer diameter d of the abutment surface 16 of the head 9 of the piston valve 8 is the diameter of the annular groove 14. Overpressure valve, characterized in that it is greater than e. 2. The utility model according to claim 1, characterized in that the area where the cylindrical outflow hole 12 opens to the cylindrical outer surface 13 of the piston valve 8 is polished smoothly. Overpressure valve. 3. The gap formed between the hole of the guide part 4 and the piston valve 8 is characterized in that it has a thickness of approximately 0.03 to 0.04 mm in the flow direction at the rear of the O-ring when viewed in the flow direction 19. , the overpressure valve according to claim 1 or 2 of the utility model registration claim.